NATURALIZATION OF FISHES. 191 



on all sides, frequently lying one above another, like a row 

 of potato hills ; but whether one pair makes more than one 

 nest has not been ascertained. The work of spawning is 

 carried on at night, and by day the fish are rarely to be 

 seen on the beds. Their ascent of the stream also occurs 

 by night. The old fish eat nothing during this season; 

 but small males are taken with their stomachs full of eggs. 

 The adult males are very different in appearance from the 

 other sex, being much deeper and thinner, with larger and 

 more pointed heads.* The lower jaw is furnished at the 

 spawning season with a singular recurved process, some- 

 times near an inch in length, which shuts into the roof of 

 the mouth; it is conical in form, either truncated or with 

 the apex bent backward. On an adult male of one pound 

 weight this was present, but not so fully developed as in 

 the larger specimens. In younger individuals it was want- 

 ing. Both jaws in this sex are so curved as to prevent the 

 closing of the mouth. A male of six inches length had a 

 forked tail, eight or nine black bars across the side, twelve 

 large vermilion spots on the side. One that measured 

 eight and one-half inches in length, has the same forked 

 tail, and the bars on the side, but they are very faint, 

 and the vermilion spots have changed to maroon; the 

 hook on the jaw not yet visible. 



" The spawning-grounds of this species are very limited. 

 Those of Long Pond are confined to Bear brook. Those 

 of Sebago are mostly limited to two or three miles of 



* This difference in the forms of the male and female is peculiar 

 to all the species of the genus Salmo at the spawning season. 



